1. Field of the Invention
This invention is related to a colloidal damper which accommodates into a closed space a mixture of a working liquid and a porous body such as silica gel, and allows the working liquid to flow-into the pores of the porous body and to flow-out from the pores of the porous body in order to dissipate the externally exerted mechanical energy, and more particularly, to a colloidal damper able to convert the externally exerted mechanical energy into electrical energy.
2. Description of the Related Art
A colloidal damper is a device which accommodates into a closed space a mixture (colloidal solution) of a working liquid and a porous body such as silica gel, and allows the working liquid to flow-into the pores of the porous body and to flow-out from the pores of the porous body in order to dissipate the externally exerted mechanical energy (see, for instance, the Patent References 1 and 2). In order to use such a colloidal damper in practical applications, previously the inventor proposed a colloidal damper able to dissipate the energy of positive damping forces (see, for instance, the Patent Reference 3), as well as a colloidal damper able to dissipate the energy of both positive and negative damping forces (see, for instance, the Patent Reference 4).
Additionally, in order to use such a colloidal damper in practical applications, the inventor proposed a colloidal damper that employs as working liquid a mixture consisted of water and antifreeze agent (see, for instance, the Patent References 5 and 9), a colloidal damper that employs as porous body, such as silica gel, a hydrophobized porous silica gel (see, for instance, the Patent Reference 6), and a colloidal damper with enhanced durability achievable by preventing the leak-out from the closed space of both the porous body and the working liquid (see, for instance, the Patent Reference 7).
Note that a passive-control colloidal damper has a constant damping characteristic (see, for instance, the Patent References 1 to 7). However, in order to efficiently dissipate the energy of vibration and/or shock caused by an external excitation (for example, the displacement excitation by the road roughness in the case of a vehicle suspension, the excitation force of an earthquake in the case of an anti-seismic system, etc.), it is necessary to adjust (control) the damping characteristic of a damper. Accordingly, the inventor proposed an active-control colloidal damper which allows the control of its damping characteristic (see, for instance, the Patent Reference 8).
By the way, fuel injection systems for injecting diesel fuel or gasoline fuel into the intake manifold or directly into the combustion chamber of an internal combustion engine are proposed in the related art (see, for instance, the Patent References 10 and 11). As illustrated in FIG. 12, such a fuel injection system 20 includes a piezoelectric actuator 21 and a controller 22. The trigger voltage “U” of the piezoelectric actuator 21 is adjusted by the controller 22 in order to control the length of the piezoelectric actuator 21, and in this way, it becomes possible to open or to close the fuel injection system 20. Concerning the fuel injection system 20, there is a correlation between the trigger voltage and the fuel pressure. For instance, if the fuel pressure varies in a higher pressure range, typically, in the range of 150 to 170 MPa, the trigger voltage has to be adjusted in the range of 220 to 260 V. Oppositely, if the fuel pressure varies in a lower pressure range, typically, in the range of 30 to 55 MPa, the trigger voltage has to be adjusted in the range of 50 to 80 V (see the Patent Reference 11).
As above-mentioned, recently even in the case of internal combustion engines it is essential to supply from an external source the electrical energy necessary for control. On the other hand, hybrid vehicles which employ both an internal combustion engine (a gasoline engine) and an electric motor have come into wide use recently. FIG. 13 presents the energetic flowchart of a hybrid vehicle. The hybrid vehicle illustrated in FIG. 13 employs a hybrid battery (NiMH) that has an electrical power of 21 kW, a DC (direct current) voltage of 288 V or 202 V, and an electrical energy of 1.8 kWh or 1.3 kWh. Consequently, in the case of this hybrid vehicle its battery provides a current of about 6.3 Ah. Electrical power is transmitted between the generator and inverter, and also between the electric motor and inverter at an AC (alternating current) voltage of 274 V or 500 V. Thus, recently the number of vehicles requiring larger amounts of electrical power is increasing, and hence, it is essential to harvest electrical energy, and to use it without wastes.
Accordingly, systems able to harvest electrical energy from the vehicle suspensions are known in the related art (see, for instance, the Patent Reference 12). Such vehicle suspension employs a structure consisted of an electromagnetic actuator mounted in parallel with a spring. Concretely, the electromagnetic actuator is consisted of a DC electric motor and a generator, and the spring can be, for example, an air spring (see FIG. 14) or a compression helical spring (see FIG. 15). In the case of this vehicle suspension, the shaft of the electromagnetic actuator is connected to a ball-screw rod, and in this way, while the ball-screw rod has a rotational movement, its counterpart, namely, the ball-screw rod has a translational movement.
Accordingly, the above-mentioned ball-screw mechanism is able to transform the up-down (bound-rebound) translational movement of a vehicle, caused by the road roughness, into the rotational movement of the shaft of the electromagnetic actuator. As a result, during a certain operation mode of the vehicle suspension, the electromagnetic actuator provides a positive damping force in response to the bound-rebound movement, and in this way, a damping effect can be obtained. Oppositely, during a different operation mode of the vehicle suspension, the electromagnetic actuator converts the mechanical energy of the bound-rebound movement into electrical energy. In other words, the electromagnetic actuator provides a negative damping force, and in this way, a generation effect can be obtained. The harvested electrical energy can be used to charge/recharge a battery. Moreover, in the above-mentioned system a controller is employed to control the operation modes of the electromagnetic actuator, the charging/discharging of the battery, etc.
Next, the ion separation effect is known as one of conventional processes to convert the mechanical energy into electrical energy. Various principles can be used in order to obtain the ion separation effect. As one of them, for instance, the Patent Reference 13 suggests a system in which a mixture of a nano-porous material and a liquid electrolyte is used. In this system, the liquid electrolyte is forced to penetrate a nanoporous material under the mechanical loading (energy) of vibration and/or shock. The ion separation effect can be obtained by selecting the diameters of nano-pores under the condition that small ions can be absorbed into pores, but large ions cannot be absorbed into pores. As a result, while the liquid absorbed into the nano-pores has an excess of small ions, the bulk liquid, namely, the liquid not absorbed into the nano-pores has an excess of large ions. By collecting the charge difference (voltage) through an electrode with a large surface area, it is possible to convert into electrical energy a part of the mechanical work of the liquid forced to penetrate the nanoporous material.